I actually bought a digital thermometer with two probes to test it, but might be meaningless without something to compare it to. Still, it makes sense to my soggy brain. And if Matt says it works, that'll do me!

I blocked the bypass with a new pump without the hole and a silicon hose - so I can swing both ways too.

The 1275's with the heated manifolds will be the same as your setup, or even a second radiator and back into the bottom hose.

Matt Reid does this modification to all his engines.I did it to mine last year, the only difference being I piped it through the inlet manifold.Nicko

Does the Matt R. mod go into the top tap or into the Heater hose pick ups?

Might concern with MD's neat little set up is that there is nothing to draw the water to the far end of the head so for the purpose of a more even cooling I am not sure it is going to work as well as other set ups using the std points of the bottom hose or the lower tank.

As far as a bypass for a stuck thermostat then it should really pump enough water to give you time to notice the temp is going up before it cooks the engine.

I am not sure that actually solves my curiousity either. but that is not to say it isn't working in many cases either.

Water takes the easiest path so to me if the pump is chugging away at idle putting through enough water to comfortably flow through the thermostat with little effort or pressure then why would the water travel to the other end of the head to escape. At speed I can understand pressure would force the water out the heater outlet, but at idle perhaps not.

Using the bottom hose or the lower radiator inlet then you will have either Venturi or Syphoning affect respectively drawing the water from the heater outlet almost regardless of what the pump is doing.

Once you have all this connected I would be interested to see if you can connect up a clear hose between your copper tube and the header tank and see if there is a change in the water flow once the thermostat opens.

I could make it easier for you and just keep asking Why each time you post???

I have seen an overheating issue recently and I have had to think about the cooling system in a bit more depth and found that that not everything works the way I thought or expected it would and because your pip is the highest point of the system I am thinking it might suffer from the same problem I saw here.

The new pipe goes into a new outlet inlet in the top tank, just like MD has done.This means the water through the new pipe gets to flow down through the radiator. If it went into the heater inlet on the bottom hose it would just resurculate uncooled.I plumbed mine through the inlet manifold too coz it looked a bit neater.

For engines without a heater the bulk of the water circulates around the radiator end of the block and head. This mod simple allows better flow to the other end and therfore more even temperature across the head.